1. Field of the Invention
This invention relates to a method for separating and quantitating the degradation products of non-enzymatic glycosylated proteins.
2. Description of the Prior Art
Glucose has been found to covalently modify a variety of proteins non-enzymatically in vivo, including hemoglobin, crystallins of lens protein, serum albumin and erythrocyte cell membrane. (Koenig et al, "Correlation Of Glucose Regulation And Hemoglobin A.sub.1C In Diabetes Mellitus", N. Engl. J. Med., 295, 417-420 (1976); Stevens et al, "Diabetic Cataract Formation: Potential Role Of Glycosylation Of Lens Crystallins", Proc. Natl. Acad. Sci. U.S.A., 75, 2918-2922 (1979); Day et al, "Non-enzymatically Glucosylated Albumin", J. Biol. Chem. 254, 595-597 (1979); and Miller et al, "Non-enzymatic Glycosylation Of Erythrocyte Membrane Proteins", J. Clin. Invest., 65, 896-901 (1980)). This non-enzymatic glycosylation reaction most probably occurs with other proteins of the body as well, particularly in the insulin-independent tissues of diabetic patients (Cerami et al, "Role Of Non-enzymatic Glycosylation In the Development Of The Sequelae Of Diabetes Mellitus", Metabolism, 28, 431-437 (1979)). The concentration of glycosylated hemoglobin has been shown to reflect mean blood glucose concentration during the preceding several weeks, and has thus provided an important new measurement for monitoring metabolic control in diabetic patients. The utility of this indicator in out-patient management of diabetes is somewhat limited, however, by the impracticality of making this measurement at frequent intervals at home, i.e. the taking of blood samples on a regular basis.
Additionally various techniques have been developed in the prior art for testing for proteinaceous materials, glucose and blood sugar conditions. Atkinson et al., U.S. Pat. No. 3,438,737, discloses a test for proteinaceous materials in various fluids, including urine, using a chromogenic indicator taking advantage of the so-called "protein error" phenomena. However, there is no indication that the proteinaceous materials are glycosylated amino acids and proteins, let alone that the test is more specific than "proteins". Haack et al., U.S. Pat. No. 3,443,903, discloses, very generally, test papers for the detection of glucose, proteins and the like in biological fluids such as urine. There is no suggestion of a test for glycosylated amino acids and peptide. Acuff, U.S. Pat. Nos. 4,168,147; 4,142,856; 4,142,857; and 4,142,858, discloses methods for determining the blood sugar condition of diabetes patients by measuring the level of a specific hemoglobin species, Hb-A.sub.1a-c, in whole blood. There is no suggestion of testing urine.
A need therefore continues to exist for a method for monitoring metabolic control in diabetic patients which is practical for home use in the management of outpatients.